Conditions Valve lesions

Aortic stenosis

A fixed obstruction to LV ejection. The gradient depends on the square of flow through the orifice, so it understates severity when output is low and overstates it with high flow; the LV adapts by concentric hypertrophy, which preserves at the cost of a stiffer diastole.

Experiment: Normal adult at rest · unchanged from its starting state

Key measurements

LV–aortic mean gradient

— mmHg

baseline not set

LV–aortic instantaneous peak gradient

— mmHg

baseline not set

— mL

baseline not set

— L/min

baseline not set

— mmHg

baseline not set

Inspect beats and technical detailsbeat selection, transient versus settled, timings

Position within the beat0.000 s

Early beats after a change are transient: the circulation is still re-balancing. A beat is called settled when three consecutive windows agree within the tolerance. Playback speed only moves the cursor over the finished simulation; it never changes the heart rate.

Compare scenariosbaseline, snapshots, axes, export

Baseline

No baseline is set.

Comparison snapshots

Keep up to three snapshots of states you want to compare with the baseline and the current state.

How comparisons are drawn

Side-by-side loops instead of an overlay Identical axes for every loop (turn off and each plot rescales to its own data)

Pressure–volume loop options

Show the ESPVR and EDPVR reference lines Shade stroke work Show the arterial elastance (Ea) line Show the right heart instead of the left

Export

Choose a version

Differences from normal: aortic valve effective orifice 3.5 → 1.2 cm²; LV Ees 2.6 → 2.9. Expected: moderate gradient, normal output.

What to look for

Large LV–aortic gradient during ejection (peak, mean and peak-to-peak differ)
LV pressure far above aortic pressure; aortic upstroke delayed
Preserved with a raised

Try it

Set values directly

Aortic valve areacm²

How this works

Effective orifice area; gradient rises with flow² / area². Not a clinical severity grade.

Changes: valves.av.eoa

Compare scenariosloads two scenarios side by side

AS vs dynamic obstruction (HOCM)

Fixed obstruction: gradient tracks flow; dynamic obstruction: gradient rises when the cavity empties (less preload, less afterload, more contractility, post-PVC).

Common misconception. A small gradient does not exclude severe stenosis when the output is low (low-flow, low-gradient AS); check the flow before grading from the gradient.

Apply it

In severe AS, a vasodilator that lowers SVR by 40% will most likely:

Raise the gradient (more flow through the same orifice) with a fall in aortic pressureLower the gradientLeave the gradient unchanged

Aortic regurgitation →

Sources & model detailsreview status, testing, limitations

Sources

Content review

Teaching text and answer keys: Proposed. None of the 2 source claims behind it has been expert reviewed. Where a question has more than one defensible answer, more than one is accepted.

Simulation testing

Finding Hemo closed-loop lumped-parameter model: Quantitatively tested. Software, conservation and qualitative pattern tests pass. Not expert reviewed; normal ranges and phenotype parameter sets are proposed teaching values.
Scenario “Normal adult at rest” is checked for: closed-system volume conservation (<0.1% over 100 beats); timestep sensitivity (<1% change in core stable measurements at dt/2); seeded repeatability; resting pressures, volumes and flows within stated textbook ranges; directional response to fluid bolus and afterload increase.

Passing these tests means the equations are solved correctly and behave as stated. It does not mean the teaching statements, parameter values or answer keys have been expert reviewed.

Limitations that matter here

Quantitative compartment model: orifice law with fixed area; no leaflet mechanics; hypertrophy represented by parameters.
Reflexes are off: no autonomic compensation follows a change (the optional baroreflex is not enabled).
Constant intrathoracic pressure -3 mmHg (respiratory swing disabled).

Technical details

Model: fh-closed-loop 0.4.0
App / content version: 0.5.0 / 0.5.0
Scenario id: normal-adult
Solver: rk4, dt 0.2 ms
Condition id: aortic-stenosis